Archery range finders are quite popular in American game hunting and there are a lot of publications via patents on such devices. One such device is disclosed in U.S. Pat. No. 3,666,368, issued on May 30, 1972 to Sprandel which deals with a sight and range finder for archers consisting of an attachment having a vertical slide on which two sliders are vertically movable.
U.S. Pat. No. 4,109,390 that issued on Aug. 29, 1978 to Smith, et al., deals with a bow sight having range finding capabilities. The device comprises a sighting frame that establishes vertically-spaced reference lines that give the apparent height of a known object at a known distance.
Knemeyer, in U.S. Pat. No. 4,995,166 that issued on Feb. 26, 1991 deals with a sight pin and top and bottom range finding pins that are mounted on a slide movable vertically relatively to the handle of an archery bow.
U.S. Pat. No. 5,351,671 that issued on Oct. 4, 1994 to Cervera deals with a sight device for mounting on the handle of an archery bow that employs a flat mounting plate and upper and lower facing rectangular mirrors orthogonally attached to the mounting plate.
Blizzard, in U.S. Pat. No. 4,984,372 that issued on Jan. 15, 1991 deals with a sighting and range finding device comprising a boxed housing having a plurality of horizontal transparent sighting elements therein having cross hair sighting reference and means for vertical adjustment.
U.S. Pat. No. 6,079,111 that issued on Jun. 27, 2000 to Williams, et al deals with a sight apparatus comprising a range finder mechanism and a pendulous sight and U.S. Patent Publication 2004/0107587 published on Jun. 10, 2004 deals with a combined target sight and range finer with a bulls-eye pin and slotted sight plate.
In a similar device, Floied, et al in U.S. Pat. No. 6,868,614 issued Mar. 22, 2005 deals with a target sight and range finder having a sight and range finder with a bulls-eye pin and slotted sight plate that has an adjustable belly bar.
All of the devices of the prior art have mechanical means or adjustability using mechanical means in order to operate.